Machine for bending and hardening leaf springs



Aug. 13, 1968 HILDEBRAND 3,396,956

MACHINE FOR BENDING AND HARDENING LEAF SPRINGS Filed Feb. 4, 1966 5 Sheets-Sheet 1 Fig.3

Fig.1

lnven tor.-

1968 F. HILDEBRAND 3,396,956

MACHINE FOR BENDING AND HARDENING LEAF SPRINGS Filed Feb. 4, 1966 s Sheets-Sheet 2 r m Mud MWM Inventor:

F. HILDEBRAND Aug. 13, 1968 MACHINE FOR BENDING AND HARDENING LEAF SPRINGS Filed Feb. 4, 1966 3 Sheets-Sheet 5 In ven tor 71,222 #145 4 M: Mmey.

United States Patent 7 Claims. 61. 266-6) ABSTRACT OF THE DISCLOSURE,"

'A machine for bending and hardening leaf springs has a series ofindependently operable frames, a bath, a conveyor to move the frames through the bath, and means for operating the frames to close and to open them.

The invention relates to the art of bending and hardening of leaf springs,..and relates more particularly to that art using leaf spring holding frames and a quenching bath.

It is known to bend and to harden leaf springs by machine. The most advanced of the machines of the prior art is formed as an octagonal star and carries 8 templatesand 8 form uppers which may be moved together and apart. In that machine now in use, the hot red leaf spring was supplied to the forward vertical section, and the leaf spring bent by closure of the parts of the form, and subsequently the form was shifted for one step and the leaf spring quenched in an oil bath. The leaf spring remained in the oil bath for two shifting steps, and during the third step it was released from the form which had opened by then, and removed from it.

In this machine of the prior art, the leaf spring remained in the oil for about a relatively short time, with attendant difficulties regarding the permanence of the bending and hardening of the leaf spring. The springs very often left the bath after the temperature had been lowered only to 200 C., oreven above that temperature. Every person familiar with this art knows, however, that it is desirable to keep the leaf spring in the hardening bath down to a temperature of about 50 C. A further disadvantage of the machines of the prior art was that they were not readily changeable from one size of leaf spring to other sizes.,In order to accomplish such changes it was necessary to remove the fixed forming parts from the octagonal star, which normally means time losses of from 25 'to 30%.

It is accordingly among the principal objects of the invention to provide a machine of the type referred to which avoids the'drawbacks of the prior art and which permits the changing from one leaf spring size to another practically without any time loss, and to hold the leaf spring while'it is cooled down to about 50 C.

It is another object of the invention to provide such a machine in which a plurality of independently operated frames is. provided, one for each leaf spring, and which are conveyed through a quenching bath.

It is a further object of the invention to provide such frames which are movable independently of each other, whereby the duration of the various treatment steps may be chosen independently of the time required for inserting the leaf springs into the frames and for removing them from the frames.

It is still another object of the invention to provide conveyor means for the aforesaid independent frames which include two driven conveyor chains, two driven bath chains, and actuating means which comprise two 3,396,956 Patented Aug. 13, I968 actuating chains that move in timed relation with respect to the conveyor chains. This offers theadvantage to vc ontrol the speed of movement in the varioussections of the path through which they are conveyed, and thus to move the frames with the leaf springs through the quenching bath at a speed considerably slower than that with which the empty frames are returned and/or the frames are loaded with springs or are latched after the springs have been placed thereinto. i

If a quenching time of 60 seconds be considered, the aforesaid octagonal star machine of the prior art, with which the spring was quenched during about 2 /2. shifting steps, yielded a succession time interval of about 20 seconds, providing for an hourly treatment of about 180 leaf springs without counting any time loss for changing to different spring sizes.

In constrast thereto, if in the instant invention there are used only 10 frames, and againa quenching time of 60 seconds is considered, there occurs a succession time interval of 6 seconds, yielding an hourly treatment production of 600 leaf springs. Where, however, as shown in the example of FIG. 1, there are used 18 frames, there will result a succession time interval of 3.33 seconds, so that about 1,080 leaf springs may be treated, hardened and cooled per hour in accordance with the instant in vention.

The temperature of the oil bath will be so chosen as to make possible a minimal cooling time; the bath should be maintained at a temperature of about from 50 C. to 60 C. Owing to the slow production figures of machines of the prior art, it was usually necessary to reheat the bath to maintain it at the desired bath temperature; this need, however, does not occur with the instant invention in view of its high production figures, and in fact the bath may even need to be cooled.

The invention accordingly comprises the features of construction, combination of elements and arrangement of parts which will be exemplified in a construction here inafter set forth and the scope of the application of which will be indicated in the claims.

For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed descripition, taken in connection with the accompanying drawings in which: i

FIG. 1 is a schematic side elevational view of a system in accordance with the instant invention, showing a chamber structure and frames being transported therein; one side wall having been removed for the sake of clarity and simplicity of presentation;

FIG. 2 is a plan view thereof;

FIG. 3 is an end elevational view thereof seen in the direction A of FIG. 1, but with the front wall removed for simplicity of presentation;

FIG. 4 is a large scale front elevational view of a frame in accordance with the invention;

FIG. 5 is a sectional view taken on the line 'V-V of FIG. 4;

FIG. 6 is a sectional view taken along the line VI.VI of FIG. 4;

FIG. 7 is a fragmentary elevational view of a detail; FIG. 8 is a fragmentary sectional view of another detai FIG. 9 is a fragmentary elevational view, partly in section, of a further detail; and

. FIG. 10 is a fragmentary elevational view of a device for unlatching the closed frame, all parts having been turned for so that the normally upright frame is shown horizontally.

As shown in FIGS. 1-3, there is provided a chamber 3 structure that comprises a container 1 that holds an oil quenching bath 2. The level of the bath 2 can be raised or lowered depending on the hourly production, namely the number of frames passing through the bath per hour, and may thus vary between a maximum level 3 and a minimum level 4 (FIG. 1).

In accordance with a preferred embodiment, the container 1 may be sunk below the level of the ground 5. The container is provided with customary inflow pipes 6 and outflow pipes 7. Heating and cooling pipes 8 may be additionally provided, in accordance with well known practice. Two columns 9 are provided that carry the driving gears and the tracks for the conveyors. Near the rear portion of the container there is provided a frame-like structure 12 that has feet and 11, and which carries vertical supports 13 and 14 that carry deflecting rolls 15, 16 and 17 for the two conveyor chains 18. Each of the conveyor chains 18 is an endless chain and, for example, may be suspended on a driving gear 19, and on a deflecting roll 20, in addition to the aforesaid deflecting rolls 15, 16 and 17 although any other suitable drive and 'suspension for the conveyor chains 18 may conveniently be chosen instead.

Upper tracks 21 and lower tracks 22 for the empty frames F are provided in the upper portion of the chamber structure, and are supported by the columns 9 and the supports 13 and 14 of the frame 12. Furthermore, upper tracks 23 and lower tracks 24 are provided for the loaded and closed and latched frames F; each frame F is loaded with a leaf spring and is closed for bending it, and holding it in the bent position, as explained below, and is latched in the closed position. Furthermore, there are provided on the chamber structure roll conveyors 25, 26 and 27, for the conveyor chains 18 and for two endless driven bath chains 28. The movement of the frames F is furthermore supported by tracks 29 and 30 that include end projections for guiding the supporting rolls, namely two upper rolls 46 and two lower rolls 57, respectively, of the frames F. As best shown in FIGS. 1 and 3, the lower rolls of each frame F engage the lower tracks 22 and 24, respectively, and the upper rolls 46 engage the upper tracks 21 and 23, respectively.

Each frame F comprises a lower base beam 31, two upright columns 32, made of precision tubing, and a yoke 33. The yoke carries at each end a sleeve 34, and each sleeve 34 surrounds a column 32 and is connected thereto by a lost motion device, namely by a splint 35 (FIG. 5) that moves in elongated opposite holes 36 of the column 32. The yoke carries tension members 37 that may be adjustably tilted and otherwise adjusted by suitable conventional means.

In accordance with a preferred embodiment, each tension member 37 carries a spring loaded presure member 38 or a roll 39 (FIGS. 4, 6). The tension members will need to be adjusted in accordance with the desired bending radius of the leaf spring to be bent and treated; they are designed to cooperate with the bending template 40 which is connected to the base beam 31.

A leaf spring 41, as shown in broken lines in FIG. 4. is first deposited onto resiliently held leaf spring supports 42 and made to abut against a central abutment member 43. During closure of the frame F, pins 421: (FIG. 6) of the supports 42 will enter into corresponding recesses 44 (FIG. 4) of the template 40.

On each of its lateral ends the yoke 33 carries an axle 45 that journals the aforesaid roll 46. Each sleeve 34 carries two diametrically opposite recesses 47 which match opposite openings 48 that are formed in each column 32.

In the open position, when the frame is either empty or is being loaded or the spring being removed therefrom, the yoke 33 is at the upper position of maximal spacing from the base beam 31, as shown in solid lines in FIGS. 4 and 5. The said upper position is determined by the splint 35 in the top position in the elongated holes 36. The yoke 33 may be moved downwardly in the direction of the arrow B from said upper position into a lower closed frame position 33a of minimum spacing from the base beam, indicated in broken lines in FIGS. 4 and 5.

In that lower position, the recesses 47 are aligned with the openings 48, and two latching elements 48a in the lower position 33a of the yoke 33 protrude through the openings 48 into the recesses 47. The latching elements 48a are urged apart into a normal extended position by a spring 49, and are pivoted inside each column 32, and each latching element has an extension 50 which are in close proximity when the latching elements are normally spread apart. A wedge element, such as a roll 51 is disposed between the extensions 50 and is movable between an inactive position (shown in solid lines in FIG. 5) adjacent said pivots during the normal position when said latching elements 48a are normally spread apart and, respectively, an active position (shown in broken lines in FIG. 5 at 51a) wherein the roll 51 spreads apart the extensions 50 and thereby retracts the latching elements 48 into the column 32 (as shown in broken lines in FIG. 5).

The roll 51 is mounted on a central rod 52 which is secured to a projecting element 53 that normally engages the underside of the base beam 31. In the active position 51a of the roll 51, however, the projecting element 53 is spaced below the underside of the base beam 31 (as shown at 53a in broken lines in FIG. 5). A spring 54 is provided to urge normally the roll 51 into the inactive position and, correspondingly, the projecting element 53 into the position of close proximity to the base beam 31 (as shown in solid lines in FIG. 5).

Guide pins 55 may be provided that guide the projecting element 53 in a guide piece 56 that is mounted in the base beam 31 and that guides also the rod 52. The previously mentioned lower rolls 57 are mounted on the base beam '31 of each frame F.

As best shown in FIG. 1, the empty frames F are transported in open positions (see the upper part of FIG. 1) by the conveyor chains 18, in positions of slight inclination, and the upper rolls 46 rolling on the upper tracks 21, and the lower rolls 57 on the lower tracks 22. The region where the leaf springs are mounted in the frames F is designated C. In the region C, the lower tracks 22 turn downwardly so that, as each frame F enters the region C, its lower section is moved downwardly, thereby tilting the frame F towards the vertical; near the point where the conveyor chains 18 are taken up by the driving gears 19, the frame F will have reached the vertical position (shown in broken lines in the region C in FIG. 1). This movement is enhanced by the track 30, as well as by guide tracks 58.

From the region C each frame F will travel downwardly for a distance in a vertical portion of its path. As the frame F descends in the region C, its projecting member 53 will engage an abutment element 59 that projects into the path of the projecting element 53, thereby temporarily arresting the downward movement of the frame F. At this point the leaf spring will be mounted in the frame F, as shown in FIG. 4; endless driven tension chains 60 (FIGS. 1, 3) are provided that engage the axles 45 and thereby press the yoke 33 downwardly until the frame F is closed, and thus the latching elements 48a engage the recesses 47 of the sleeves 34 of the yoke 33. In that instant, a cam 61 (FIG. 7) that is mounted on the yoke 33 engages the rolls 62 of a pivoted bell crank lever 63 and thereby raises a rod 64. The rod 64, on the other hand, as best shown in FIG. 8, by its being pulled upwardly moves a bell crank lever 65 that is connected by a bolt 66 to the abutment element 59 and thereby retracts the abutment element 59 from the path of the projecting element 53. This enables the closed frame F to continue on its downward path, driven by the tension chains 60, until it is taken over by the bath chains 28.

In order to prevent the abutment element 59 from snapping back after the cam 61 has passed the roll 62,

a safety device is provided that is shown in FIG. 9. The safety device comprises a 'spring'pressed latch 67 which engages a lateral'rece'ss of the abutment element 59. The abutment element 59 is also spring pressed. The latch 67 is guided in a housing 71, and carries a pin 70. The housing 71 of the latch 67 includes a sleeve 72 that guides a cam 73 that moves parallel to the movement of the abutment element 59, but at right angles to the movement of the latch 67. When the cam 73 is moved to the left-(FIG. 9), itwill move the pin and therewith the latch 67 downwardly (FIG. 9), thereby releasing the abutment element 59 to be moved to the left under the pressure of its spring 68. The cam 73 is driven by a rod 75 which is moved, byway of two-armed levers 76 and 77, from a rod 78 (FIG. 8). The lever 77 carries a roll 79 which forms a cam follower for a release cam 80 that is arranged on the base beam-31 and is arranged approximately oppositely with respect to the cam 61 of the yoke 33.

The abutment elements 59 thus will return to their posi tion of projection into the path of the projecting elements 53 after the base beam 31 and therewith the release cams 80 have passed the roll 79. Thus, the abutment elements 59 are in position to stop the next empty frame F to be loaded with the leaf spring.

After the frames F have passed through the bath (see the lower part of FIG. 1), they will reach the unloading region D, where the frames are opened, in accordance with an arrangement shown in FIG. 10. (FIG. 10, as previously mentioned, has been turned around for 90; actually, the columns should be upright, rather than horizontal as shown.)

Claws 81 are provided that project into the path .of the projecting elements 53. The claws 81 are mounted on levers 82 and 83 that are tiltable on bolts 84 and 85. The free ends of the levers 82 and 83 have elongated holes that surround a pin 86. The pin 86 is mounted resiliently by means of a spring 87. As the conveyor chains move the frame F, the projecting elements 53 will be retracted (into the position 53a, see FIG. 5), whereby the latching elements 48a will be retracted into the column 32, thereby releasing the yoke 33.

The lever 82 has a further arm 88 that is pivoted to a rod 89 that engages one arm of a two-armed lever 91 that carries on its other arm a roll 91. When the yoke 33 has reached the upper position (shown at 33b in broken lines in FIG. its cam 61 will have moved the roll 91, the lever 90, the arm 88 and the levers 82 and 83 to open the claws 81, so that the frame F can thereafter be transported in open position; the treated leaf spring may be removed out of the frame in the usual conventional manner, while the frame continues to be transported by the conveyor chains, to be reused.

Although the conveyor chains 18 and the bath chains 28 are circulating continuously, the frames F may nonetheless be moved throughout the various regions of the chamber structure at different speeds, for instance slower through the bath, as compared to the upper portion of the chamber structure, providing a complete control for the hardening treatment. As best shown in the lower part of FIG. 1, the tracks 23 and 24 are so spaced apart from each other, as compared to the spacing between the rolls 46 and 57 .on the closed frames F, that the frames will be in an inclined position. This inclined position promotes the rinsing of the leaf springs, while the inclined position of the frames'after the bath and during the return movement promotes the dripping of the oil from the frames.

The frames F close positively. The tension members 37, though resiliently mounted, are provided with their springs only to compensate for inaccuracies and differences in thickness of material. They are much stronger than the force needed to bend the hot leaf springs.

I wish it to be understood that I do not desire to be limited to the exact details of construction shown and described, for obvious modifications will occur to a person skilled in the art.

Having thus described the invention, what I claim as new and desire to be secured by Letters Piatent is as follows:

1. Ina machine, for use in bending and hardening leaf springs, a plurality of frames each operableindependently of the other frames to be closed and respectively opened for releasably clamping and holding a leaf spring, a chamber structure comprisingreservoir means establishing a container for a quenching bath, closure actuating means operable for the closing and latching of each frame, release actuating means operable for the unlatching and the opening of each frame subsequently, and conveyor means operable for guiding and transporting'said frames in ,a predetermined path throughout 'said bath, said conveyor means comprising two endless driven I conveyor chains spaced apart from eachother and two endless driven bath chains spaced from each other, said actuating means comprising two endless driven. actuating chains moving in timed relation withre'spe'ct to the conveyor chains.

2. In a machine, as claimed in claim 1, each frame comprising latching means movable between latching and release positions, respectively, releasing means for said latching means in driving connection with said latching means and movable between a retracted position when said latching means is in the latching position and, respectively, an extended position wherein it moves said latching means to said release position, said actuating means engaging said releasing means of each frame for moving it between the retracted and extended positions, for closing and latching and, respectively, unlatching and opening the frame.

3. In a machine, as claimed in claim 2, each frame comprising a base beam and two columns, and a yoke engaging said columns and guided thereon for movement to and from a closed frame position of minimum spacing of the yoke from the base beam in which position said yoke is adapted to clamp and to hold a leaf spring in the frame, said columns being hollow and each having at least one opening, said yoke comprising two sleeves, each engaging a column and having at least one recess matching said opening and in alignment therewith in the closed position of said frame, said latching means comprising at least .one latching element disposed inside each column adjacent said opening, a spring urging said latching element into the latching position wherein the element protrudes through said opening to engage said recess of the yoke when the yoke is in the said closed frame position.

4. In a machine, as claimed in claim 2, each frame comprising a base beam and two columns, and a yoke engaging said columns and guided thereon for movement to and from a position of minimum spacing from the base beam in which position it is adapted to clamp and to hold a leaf spring in the frame, said columns being hollow and each having two opposite openings, said yokes comprising two sleeves, each engaging a column and having two recesses matching said openings and aligned therewith in the closed position of said frame, said latching means comprising two latching elements each pivoted adjacent one .of said openings and having an extension, a spring between said latching elements urging them apart and into a latching position in which they extend through said aperture and into the recess aligned therewith in the closed position, said releasing means comprising a wedge element positioned between the extensions of said two latching elements and being movable between an inactive position adjacent said pivots when said latching elements are in the latching position and, respectively, an active position spaced apart from said pivots wherein said wedge element spreads apart said extensions thereby retracting the latching elements into said column, and a projecting element connected to said wedge element and movable therewith between retracted and extended positions, respectively.

5. In a machine, as claimed in claim 4, said engaging means comprising at least one abutment element disposed in the path of said projecting element of said base beam in said chamber at a position of said path at which the closure of each frame is to commence, and cam and cam follower means between each yoke and said abutment element operable to remove said abutment element out of the path of the base beam after the yoke has been moved to the closure position on said frame.

6. In a machine, as claimed in claim 5, and restoring means comprising cam and cam follower means including resilient means intermediate said base beam and said abutment element and operable for returning said abutment element into the position in the path of said projecting element.

7. In a machine, as claimed in claim 4, said engaging means comprising spring pressed claws disposed in the path of said projecting element and being operable to engage said projecting element thereby to release said latching means, and claw opening means including cam and cam follower means operable for opening said claws against the spring power after the yoke has been completely .opened.

References Cited UNITED STATES PAT NT Gueutal et a1. 266- 6 Hendrickson 266 -6 Bowers et a1. 266-6 Grell 2664-6 Rockhoff 266 -6 Hobracht 266:6 Daly ,95-94 Miklic 266 -6 Gogan 2666 Custer et a1. .118 -423v X Bablik 118 423.X

Johnson et a1. .118--423X J. SPENCER OVERHOLSER, Primary Examiner.

R. S. ANNEAR, Assistant Examiner. 

